One issue with many conventional frequency references is stability. Conventional techniques for reaching frequency stabilities (i.e., Δf/f) in the range of 10−14 or better use cryogenically cooled crystal oscillators, cesium fountain clocks, and/or highly stabilized optical clocks. Many of these conventional frequency references are not attractive due to their large size, weight, complexity and/or power consumption.
Thus, there are general needs for improved precision oscillators and methods for generating ultra-stable frequency references. There are also general needs for precision oscillators and methods for generating ultra-stable frequency references that are less complex than many conventional systems. There are also needs for low-phase noise and ultra-stable oscillators that are suitable for use in radar systems, communication systems and signal-collection systems. There are also needs for ultra-stable oscillators for use in systems that require synchronization. There are also needs for ultra-stable oscillators suitable for use in difficult EMI environments. There are also needs for an ultra-stable frequency reference that can provide a frequency stability that exceeds 10−14.